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authorTejun Heo <tj@kernel.org>2016-02-09 17:59:38 -0500
committerTejun Heo <tj@kernel.org>2016-02-09 17:59:38 -0500
commitf303fccb82928790ec58eea82722bd5c54d300b3 (patch)
tree20030c728af441a4efa01c2612be4883bd431115 /lib
parentef557180447fa9a7a0affd3abb21ecceb4b5e125 (diff)
workqueue: implement "workqueue.debug_force_rr_cpu" debug feature
Workqueue used to guarantee local execution for work items queued without explicit target CPU. The guarantee is gone now which can break some usages in subtle ways. To flush out those cases, this patch implements a debug feature which forces round-robin CPU selection for all such work items. The debug feature defaults to off and can be enabled with a kernel parameter. The default can be flipped with a debug config option. If you hit this commit during bisection, please refer to 041bd12e272c ("Revert "workqueue: make sure delayed work run in local cpu"") for more information and ping me. Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.debug15
1 files changed, 15 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ecb9e75614bf..8bfd1aca7a3d 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1400,6 +1400,21 @@ config RCU_EQS_DEBUG
endmenu # "RCU Debugging"
+config DEBUG_WQ_FORCE_RR_CPU
+ bool "Force round-robin CPU selection for unbound work items"
+ depends on DEBUG_KERNEL
+ default n
+ help
+ Workqueue used to implicitly guarantee that work items queued
+ without explicit CPU specified are put on the local CPU. This
+ guarantee is no longer true and while local CPU is still
+ preferred work items may be put on foreign CPUs. Kernel
+ parameter "workqueue.debug_force_rr_cpu" is added to force
+ round-robin CPU selection to flush out usages which depend on the
+ now broken guarantee. This config option enables the debug
+ feature by default. When enabled, memory and cache locality will
+ be impacted.
+
config DEBUG_BLOCK_EXT_DEVT
bool "Force extended block device numbers and spread them"
depends on DEBUG_KERNEL